The star - who shared a video of the amusing moment on Instagram - could be seen eating from a pyramid of cupcakes which each had a letter spelling out 'BRUNO'.

Clinking his glass to show his approval, the 'Just The Way You Are' singer commanded: "Again!"

Bruno hinted at just how surreal the moment was, and joked that it meant he has truly "made it".

He wrote: "You know you've made it when you can hire Ed Sheeran to sing you Happy Birthday #ExtraForever #HappyBrunoMarsDay!"

Bruno and Ed were hanging out backstage at Bridgestone Arena in Nashville, Tennessee on the former's world tour just hours before he went on stage.

He is currently being joined by Ciara, after previous support act Cardi B decided to step away to spend more time with her newborn daughter Kulture Kiari.

The celebrations came a day ahead of the 2018 American Music Awards, which will see the star nominated for both Favourite Male Artist in the Soul/R&B genre, and Best Tour.

Meanwhile, Ed will be competing against his friend in the latter category, while he has also found himself on the shortlist for a number of others, including favourite pop or rock male artist, and Artist of the Year.